Signal stabilization in a non-resistive contact sensor assembly

ABSTRACT

A non-resistive contact sensor assembly includes an electric field sensor device, including a dry electrode component for receiving an electrical signal from an object of interest and a signal processing component for processing the electrical signal, and a casing in which the signal processing component is surrounded or embedded. The processing component may include communications capabilities.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is U.S. continuation patent application of, andclaims priority under 35 U.S.C. §120 to, U.S. nonprovisional patentapplication Ser. No. 13/834,918, filed Mar. 15, 2013, which patentapplication is incorporated by reference herein, and which applicationis itself a U.S. non-provisional patent application of, and claimspriority under 35 U.S.C. §119(e) to, U.S. provisional patent applicationSer. No. 61/695,986 to Dawson, filed Aug. 31, 2012 and entitled “SIGNALSTABILIZATION IN A NON-RESISTIVE CONTACT SENSOR ASSEMBLY,” which '986application is incorporated by reference herein in its entirety.Additionally, the entirety of each of the following co-pending,commonly-assigned U.S. patent applications, and any applicationpublication thereof, is expressly incorporated herein by reference:

-   -   (a) U.S. provisional patent application Ser. No. 61/671,647 to        Dawson, filed Jul. 13, 2012 and entitled “REDUCING MOVEMENT AND        ELECTROSTATIC INTERFERENCE IN A NON-RESISTIVE CONTACT SENSOR        ASSEMBLY;”    -   (b) U.S. provisional patent application Ser. No. 61/759,827 to        Dawson, filed Feb. 1, 2013 and entitled “SIGNAL STABILIZATION IN        A DIELECTRIC SENSOR ASSEMBLY;”    -   (c) U.S. non-provisional patent application Ser. No. 13/834,664,        filed Mar. 15, 2013, and entitled, “REDUCING MOVEMENT AND        ELECTROSTATIC INTERFERENCE IN A NON-RESISTIVE CONTACT SENSOR        ASSEMBLY;” and    -   (d) U.S. non-provisional patent application Ser. No. 13/835,762,        filed Mar. 15, 2013, and entitled, “SIGNAL STABILIZATION IN A        DIELECTRIC SENSOR ASSEMBLY.”

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under contract numberW911NF-12-C-0004 awarded by DARPA. The government has certain rights inthe invention.

COPYRIGHT STATEMENT

All of the material in this patent document is subject to copyrightprotection under the copyright laws of the United States and othercountries. The copyright owner has no objection to the facsimilereproduction by anyone of the patent document or the patent disclosure,as it appears in official governmental records but, otherwise, all othercopyright rights whatsoever are reserved.

BACKGROUND OF THE PRESENT INVENTION

1. Field of the Present Invention

The present invention relates generally to electric field sensors, and,in particular, to signal stabilization in a non-contact resistivecontact sensor assembly.

2. Background

Conventional electrodes act as a current transducers converting ioniccurrents into electronic ones so electrophysiological status can beassessed. The uses for this approach are many and broadly range fromassessment of neural (EEG), cardiac (ECG), and skeletal (EMG) muscleactivity.

This approach requires conductive contact with the source and hasinherent problems. The first of these is the requirement of clean skinexposure. This requirement may compromise continuous usability due tothe effects of environmental contaminants, both on the skin and in theatmosphere; extremes of temperature and their resulting general effecton skin due to physiological reactions such as “goose bumps” andexcessive sweating as well as other phenomena; and potential reactionsto conductive materials. The process of preparing skin and securing agood conductive contact can also decrease compliance, especially in ifintended for continuous day to day use. Furthermore, during exercise,the physicality can result in electrodes being displaced. Other issuesinclude shorting between electrodes, especially when placed in closeproximity to each other, and charge transfer which has potential safetyimplications as well as the issue of the measurement process corruptingthe signal.

The problems, outlined above, may be at least partially solved by theuse of capacitive electrodes (non-resistive contact sensors) as theyacquire signals through capacitive coupling, not requiring resistivecontact with the source. They provide many benefits, including the factthat no electrical contact is required, and so no skin preparation orconducting pads are necessary and they can be readily moved or relocatedto get an optimal signal. In addition, they can be miniaturized, theyhave very low power requirements, and they can be embodied as passiveelectric field sensors with the result that adjacent sensors do notinterfere with each other.

The use of capacitive electrodes for electrophysiological monitoring isnot a recent innovation, with Richardson describing it for acquisitionof the cardiac signal in 1967¹. This system was, however, flawed beingprone to problems including poor signal to noise ratio, voltage drift,electrostatic discharge and parasitic capacitance. These are stillproblems with capacitive sensor technologies today. Many of thoseproblems have been addressed, at least partially, but problems withsignal stability interference still plague this technology. Signalstability interference is especially problematic during movement.Movement may lead to a variety of issues that may compromise continuoussignal acquisition including contact electrification between the bodysurface and the sensor electrode; charge build-up on the body resultingin baseline shift and potential saturation if occurs too rapidly; andmovement of the sensor relative to the body that can also lead tobaseline shift and saturation (railing). ¹ The insulated electrode: apasteless electrocardiographic technique. Richardson P C. Proc. Annu.Conf. on Engineering in Medicine and Biology 7: 9-15 (1967)

When dry contact electrodes are placed in direct contact with a person,and particularly when they are moved, triboelectric effects (electricalcharges created by sliding friction and pressure) are frequentlygenerated. Triboelectric effects of this nature may cause contactelectrification where static charges may be delivered to the pick-upelectrode. This static charge can produce a near-direct current (DC) orvery low frequency drift in the sensor that may interfere with thephysiological alternating current (AC) signal that is being measured ormay saturate the sensor causing railing, after which the sensor takestime to return to being able to produce a usefulphysiologically-relevant output. If the electrode moves relative to thebody, it will also pick up a geoelectric displacement signal. That is,the effect of the body, an electrically active structure, moving throughthe geoelectric field, which is on the order of 100 Vm⁻¹, will causerelative polarization of the sensor that will displace the baseline andmay cause the sensor to saturate. An additional source of interferenceis that of clothing moving on the body. As clothing moves on the body,charge separation can occur when materials that are separated on thetriboelectric series donate or receive electrons from each other. Aftera material becomes charged it may discharge onto the surface where anelectric potential is being measured, thereby interfering with signalacquisition.

Various issues can arise as a result of these various forms ofinterference. For example, issues may arise in the signal acquisitionphase due to corruption of the signal from local electrical activity, inthe signal referencing phase due to poor referencing of the signal to anappropriate earth, and during the transfer of the signal to processingunits where the signal may be susceptible to interference. Thus, a needexists for devices, methods, and/or systems for reducing interferenceand stabilizing the signals being acquired and processed.

SUMMARY OF THE PRESENT INVENTION

Broadly defined, the present invention according to one aspect is anon-resistive contact sensor assembly, including: an electric fieldsensor device, including a dry electrode component for receiving anelectrical signal from an object of interest and a signal processingcomponent for processing the electrical signal; and a casing in whichthe signal processing component is surrounded or embedded.

In a feature of this aspect, the signal processing component includes anA/D converter for converting the electrical signal from the object ofinterest to a digitized signal.

In another feature of this aspect, the signal processing component iselectrically shielded from the dry electrode component by an internalpartition. In further features, the internal partition is provided inthe form of a circuit board; the signal processing component is an A/Dconverter, and wherein the assembly further comprises at least oneadditional signal processing component, electrically shielded from thedry electrode component by the internal partition, for processing theoutput of the A/D converter; the assembly further includes an amplifiercomponent that is distinct from the dry electrode component, and whereinthe signal processing component is electrically shielded from theamplifier component by the internal partition; the internal partition isa structural extension of the casing; the signal processing component isa transmitter for transmitting a resulting digitized signal to anotherlocation (wirelessly and/or or over a data cable physically connected tothe assembly); and/or the assembly further includes a circuit board onwhich the signal processing component is mounted, and wherein thecircuit board is electrically shielded from the dry electrode componentby the internal partition.

In another feature of this aspect, the casing is part of a housing forthe assembly, and wherein the dry electrode component is exposed to theexterior of the housing. In a further feature, the casing iselectrically isolated from the dry electrode component.

In another feature of this aspect, the dry electrode component isadapted to avoid resistive contact with a surface of the object ofinterest. In a further feature, the dry electrode component is adaptedto avoid resistive contact with human skin.

In another feature of this aspect, the casing is adapted to made directresistive contact with a surface of the object of interest. In a furtherfeature, the dry electrode component is adapted to avoid resistivecontact with human skin.

In another feature of this aspect, the assembly is in the form of asensor head.

In another feature of this aspect, the casing is electrically grounded.In further features, the casing is electrically grounded via a groundconnection to a power cable physically connected to the assembly; and/orthe casing serves as a reference with regard to the electrical signalfrom the object of interest.

In another feature of this aspect, the casing is a conductive casingthat acts as an electrical reference with regard to the electricalsignal from the object of interest.

Broadly defined, the present invention according to another aspect is anon-resistive contact sensor assembly, including: an electric fieldsensor device, including a dry electrode component for receiving anelectrical signal from an object of interest by capacitively couplingwith the entity; a housing in which the signal processing component issurrounded or embedded; and an anode and a cathode, distinct from thedry electrode component, that together provide a stable surface field,thereby allowing more focused acquisition of the electrical signal fromthe object of interest.

In a feature of this aspect, the distinct anode and cathode are disposedin the housing with the dry electrode component.

In another feature of this aspect, the distinct anode is exterior to thehousing.

In another feature of this aspect, the distinct cathode is exterior tothe housing.

In another feature of this aspect, the stable surface field issubtracted computationally during post-acquisition processing of theelectrical signal from the object of interest.

In another feature of this aspect, the assembly is in the form of asensor head.

Broadly defined, the present invention according to another aspect is anon-resistive contact sensor assembly, including: an electric fieldsensor device, including a dry electrode component for receiving anelectrical signal from an object of interest by capacitively couplingwith the entity; a cover in which the signal processing component issurrounded or embedded; and a biasing structure, disposed on the outsideof the cover, that are adapted to press the dry electrode componentagainst a surface of the object interest when biased by an externalstructure.

In a feature of this aspect, the biasing structure is a spring. In afurther feature, the spring is a mechanical spring with a polymeric,metallic, and/or fiber material construction.

In another feature of this aspect, the biasing structure is comprised ofcompressive material. In a further feature, the compressive material isselected from a group comprising rubber, felt, elastomeric, polymeric,closed cell foam and analogues.

In another feature of this aspect, the assembly is arranged in a helmetthat comprises the external structure.

In another feature of this aspect, the assembly is arranged beneath abelt that comprises the external structure.

In another feature of this aspect, the assembly is arranged beneathjewelry that comprises the external structure

In another feature of this aspect, the assembly is arranged beneath anarticle of clothing that comprises the external structure.

In another feature of this aspect, the assembly is arranged in a pieceof furniture that comprises the external structure.

In another feature of this aspect, the assembly is arranged in a vehicleseat that comprises the external structure. In features of this aspect,the vehicle seat is an automobile seat, an airplane seat, a raillocomotive seat, or a wheelchair seat.

In another feature of this aspect, the assembly is in the form of asensor head.

Broadly defined, the present invention according to another aspect is anon-resistive contact sensor assembly as shown and described.

Broadly defined, the present invention according to another aspect is asensor head for a non-resistive contact sensor assembly as shown anddescribed.

Broadly defined, the present invention according to another aspect is amethod of reducing movement in a non-resistive contact sensor assembly,as shown and described.

Broadly defined, the present invention according to another aspect is amethod of signal stabilization in a non-resistive contact sensorassembly, as shown and described.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, embodiments, and advantages of the present inventionwill become apparent from the following detailed description withreference to the drawings, wherein:

FIG. 1 is a schematic diagram of a non-resistive contact sensor assemblyin accordance with a first preferred embodiment of the presentinvention;

FIG. 2 is a schematic diagram of a non-resistive contact sensor assemblyin accordance with another preferred embodiment of the presentinvention;

FIG. 3 is a schematic diagram of a hybrid sensor assembly in accordancewith another preferred embodiment of the present invention;

FIG. 4A is a schematic diagram of a non-resistive contact sensorassembly in accordance with another preferred embodiment of the presentinvention;

FIG. 4B is a schematic diagram of a non-resistive contact sensorassembly in accordance with another preferred embodiment of the presentinvention;

FIG. 5A is a fragmentary, partially schematic top view of a portion of awearable sensor belt in accordance with one or more preferredembodiments of the present invention;

FIG. 5B is a fragmentary, partially schematic top view of a portion ofanother wearable sensor belt in accordance with one or more preferredembodiments of the present invention;

FIG. 6 is a fragmentary, partially schematic front view of the wearablesensor belt of FIG. 5A;

FIG. 7 is a fragmentary, partially schematic front view of the wearablesensor belt of FIG. 6, shown with the sensor casing removed;

FIG. 8 is a fragmentary, partially schematic top view of the portion ofthe wearable sensor belt of FIG. 5A, shown in use against the chest of ahuman;

FIG. 9 is a front perspective view of a an exemplary wearable sensorbelt attached around the chest of a human wearer in accordance with oneor preferred embodiments of the present invention;

FIG. 10 is a fragmentary front perspective view of the wearable sensorbelt of FIG. 9;

FIG. 11 is an exploded fragmentary front perspective view of thewearable sensor belt of FIG. 10; and

FIG. 12 is an exploded fragmentary rear perspective view of the wearablesensor belt of FIG. 10.

DETAILED DESCRIPTION

As a preliminary matter, it will readily be understood by one havingordinary skill in the relevant art (“Ordinary Artisan”) that the presentinvention has broad utility and application. Furthermore, any embodimentdiscussed and identified as being “preferred” is considered to be partof a best mode contemplated for carrying out the present invention.Other embodiments also may be discussed for additional illustrativepurposes in providing a full and enabling disclosure of the presentinvention. As should be understood, any embodiment may incorporate onlyone or a plurality of the above-disclosed aspects of the invention andmay further incorporate only one or a plurality of the above-disclosedfeatures. Moreover, many embodiments, such as adaptations, variations,modifications, and equivalent arrangements, will be implicitly disclosedby the embodiments described herein and fall within the scope of thepresent invention.

Accordingly, while the present invention is described herein in detailin relation to one or more embodiments, it is to be understood that thisdisclosure is illustrative and exemplary of the present invention, andis made merely for the purposes of providing a full and enablingdisclosure of the present invention. The detailed disclosure herein ofone or more embodiments is not intended, nor is to be construed, tolimit the scope of patent protection afforded the present invention,which scope is to be defined by the claims and the equivalents thereof.It is not intended that the scope of patent protection afforded thepresent invention be defined by reading into any claim a limitationfound herein that does not explicitly appear in the claim itself.

Thus, for example, any sequence(s) and/or temporal order of steps ofvarious processes or methods that are described herein are illustrativeand not restrictive. Accordingly, it should be understood that, althoughsteps of various processes or methods may be shown and described asbeing in a sequence or temporal order, the steps of any such processesor methods are not limited to being carried out in any particularsequence or order, absent an indication otherwise. Indeed, the steps insuch processes or methods generally may be carried out in variousdifferent sequences and orders while still falling within the scope ofthe present invention. Accordingly, it is intended that the scope ofpatent protection afforded the present invention is to be defined by theappended claims rather than the description set forth herein.

Additionally, it is important to note that each term used herein refersto that which the Ordinary Artisan would understand such term to meanbased on the contextual use of such term herein. To the extent that themeaning of a term used herein—as understood by the Ordinary Artisanbased on the contextual use of such term—differs in any way from anyparticular dictionary definition of such term, it is intended that themeaning of the term as understood by the Ordinary Artisan shouldprevail.

Regarding applicability of 35 U.S.C. §112, ¶6, no claim element isintended to be read in accordance with this statutory provision unlessthe explicit phrase “means for” or “step for” is actually used in suchclaim element, whereupon this statutory provision is intended to applyin the interpretation of such claim element.

Furthermore, it is important to note that, as used herein, “a” and “an”each generally denotes “at least one,” but does not exclude a pluralityunless the contextual use dictates otherwise. Thus, reference to “apicnic basket having an apple” describes “a picnic basket having atleast one apple” as well as “a picnic basket having apples.” Incontrast, reference to “a picnic basket having a single apple” describes“a picnic basket having only one apple.”

When used herein to join a list of items, “or” denotes “at least one ofthe items,” but does not exclude a plurality of items of the list. Thus,reference to “a picnic basket having cheese or crackers” describes “apicnic basket having cheese without crackers,” “a picnic basket havingcrackers without cheese,” and “a picnic basket having both cheese andcrackers.” Finally, when used herein to join a list of items, “and”denotes “all of the items of the list.” Thus, reference to “a picnicbasket having cheese and crackers” describes “a picnic basket havingcheese, wherein the picnic basket further has crackers,” as well asdescribes “a picnic basket having crackers, wherein the picnic basketfurther has cheese.”

In various aspects, the present invention relates to methods ofattenuating or eliminating unwanted movement or electrostaticinterference on signals acquired via non-resistive contact sensors fromvarious entities, both biological and other. Such sensors may be used bythemselves, or may be used in combination with other sensors. The sensordata is utilized for detecting properties of the entities.

For biological entities, the invention utilizes an electric field sensoror sensors for the measurement of the structural and functionalcharacteristics of organs and other structures where the electric fieldsensor does not have resistive contact with the organism, conferringmultiple advantages. In various aspects, the present invention relatesto sensors, sensor housings, fastenings and sensor systems includingdevices and installations for assemblies for detecting structural andfunctional signatures associated with electric potentials that maydetect a displacement signature within the geomagnetic field, and/orspecific components and/or structures that are a component of thatentity or entities. There is preferably no resistive contact between theentity and the signal transduction component of the electric fieldsensor or sensors. Other sensor types may be added in to provide furtherinformation, such as for the identification and elimination orattenuation of unwanted electrostatic or movement signal associated withthe recording of non-resistive contact electric fields from that entity,in whatever state, such as during active or passive movement.

In particular, the present invention, in various aspects, relates tonovel methods and apparatuses for stabilizing the target signal whenusing an electric field sensor or sensors of the type that does not haveresistive contact with the entity, generally an organism, which is beingmonitored. In various aspects, the invention relates to combinations andpermutations of: applying an electric field to electrically stabilizethe sensor zone; the use of a conductive casing to act as a referencefor the signal that is being acquired; the use of an analog to digitalconverter in the sensor head to digitally fix the signal; the use of abarrier (guard or shield) between the analog to digital converter tomitigate signal corruption the converter; a logic board to process thesignal in the sensor head; a compressive material, spring, or anothercomponent in tension against another fixed structure, such as a helmet,to hold the referencing component and/or the electrode firmly on thesurface of the entity being measured; a cable or wireless transmitter totransmit the digitized signal; and/or a resistive contact electrode thatmay be incorporated into the reference casing or used as a separatecomponent to add signal acquisition resilience.

Referring now to the drawings, in which like numerals represent likecomponents throughout the several views, one or more preferredembodiments of the present invention are next described. The followingdescription of one or more preferred embodiment(s) is merely exemplaryin nature and is in no way intended to limit the invention, itsapplication, or uses.

FIG. 1 is a schematic diagram of a non-resistive contact sensor assembly10, or at least a sensor head thereof, in accordance with a firstpreferred embodiment of the present invention. The sensor assembly 10includes a electric field sensor device 12, an analog-to-digital (A/D)converter 18, an internal partition 22, a power and data cable 24, and ahousing 14. The sensor device 12 is at least partially surrounded by, orembedded in, the housing 14, at least portions of which may be made ofanti-triboelectric material. In various respects, the sensor assembly 10and sensor device 12 may have one or more characteristics described inthe '664 application.

The sensor device 12 includes a dry electrode component 16 that isexposed to the exterior of the housing 14 and is arranged to avoidresistive contact with the skin or other surface 20 on which the sensorassembly 10 is placed. However, the sensor electrode 16 is capacitivelycoupled to the skin or other surface 20 of the entity being analyzed andmay be in physical contact with the surface 20 so long as resistivecontact is avoided. In at least some embodiments, physical contact isavoided so as to avoid resistive contact.

The housing 14 includes a conductive casing (shielding) 15 that makesdirect resistive contact with the skin or other surface 20 on which thesensor assembly 10 is placed but is electrically isolated from theelectrode 16. The casing 15, which as noted makes resistive contact withthe surface 20, is grounded by a ground connection 26 to the power anddata cable 24 to the unit 10. The casing 15 may thus serve as areference with regard to a target signal 30 from the object of interest.

After the signal from the electrode 16 is amplified, it is converted toa digital signal by the A/D converter 18. Notably, the A/D conversion iscarried out within the confines of the sensor casing 15, and in at leastsome embodiments, the amplification is likewise carried out within theconfines of the sensor casing 15. The A/D converter 18 is also shieldedfrom the electrode 16 itself by the internal partition 22, which isdesigned to provide an electrical field barrier against the electrode 16and the amplification thereof. In this regard, it will be appreciatedthat in at least some embodiments, amplification likewise takes place onthe opposite side of the partition 22 from the A/D converter 18.Advantageously, the shielding offered by the partition 22 helps toprevent the A/D converter 18 from being affected by interference causedby various electrical effects. The partition 22 may take any of avariety of forms, including as a structural extension of the casing 15.

Other processing components may also be shielded from the electrode 16and amplification by the partition 22. In at least some embodiments, thepartition 22 is provided in the form of a circuit board, and the otherprocessing components may be disposed on the circuit board 22. In otherembodiments, a circuit board is provided, but is separate from thepartition 22 and is shielded by the partition 22 from the electrode 16and amplification. Furthermore, in addition to, or included within, theother processing components, a transmitter (not shown) may be provided,within the casing 15 and shielded by the circuit board or otherpartition 22, for transmitting a resulting digitized signal to anotherlocation. Such transmission may occur wirelessly or over the power anddata cable 24, and is similar protected from interference by the casing15 and the circuit board or other partition 22.

FIG. 2 is a schematic diagram of a non-resistive contact sensor assembly110, or at least a sensor head thereof, in accordance with anotherpreferred embodiment of the present invention. The sensor assembly 110includes an electric field sensor device 112 at least partiallysurrounded by, or embedded in, a cover 114, which may be ofanti-triboelectric material. In various respects, the sensor assembly110 and sensor device 112 may have one or more characteristics describedin the '664 application. Furthermore, the sensor device may incorporatecharacteristics of the sensor device 12 of FIG. 1, described previously.The sensor device 112 of FIG. 2 includes a non-resistive contactelectrode component 116, an anode 128, and a cathode 132. In at leastsome embodiments, the non-resistive contact electrode component 116 isinterior to the cover 114, but this is not required. Furthermore,although in the illustrated embodiment the anode 128 and cathode 132 areexterior to the cover 114, it will be appreciated that in someembodiments, it may be possible to locate the anode 128 and cathode 132interior to the cover 114.

An electric field 140 is produced by the anode 128 and cathode 132 tostabilize the electric potential, and particularly the surface electricpotential, around the sensor assembly 110. This, in turn, allows morefocused acquisition of the target field (signal) 130 being produced bythe entity.

In FIG. 2, the sensor assembly 110 is shown making contact with thesurface 20 of the entity being measured or analyzed. The electrode 116capacitively couples to the entity to measure the target signal 130. Theanode 128 produces an electron flow 140 toward the cathode 132, therebyproviding a stable surface field. This field can be subtractedcomputationally as needed during post-signal acquisition processing.

FIG. 3 is a schematic diagram of a hybrid sensor assembly 210, or atleast a sensor head thereof, in accordance with another preferredembodiment of the present invention. In this sensor assembly 210, tworegions 242,244 surround a non-resistive contact electric field sensordevice 212, including a dry electrode component (not separately shown).The inner region 244 could include a triboelectrically neutral orrelatively neutral material, such as but not limited to cotton. Onepurpose in using such material is to avoid the buildup of electrostaticor other charges, because the material will be at least relativelyresistant to, if not able to avoid altogether, accepting or donatingelectrons. The outer region 242 includes a conductive material and mayinclude fastening/elastic/compressive materials. In various respects,the sensor assembly 210 and its components may have one or morecharacteristics described in the '664 application.

The sensor assembly 210 is used in conjunction with a conventionalresistive contact electrometer to provide two interrogation routes ofthe electrical activity of the entity being measured, thereby enhancingthe robustness of the overall system. At the periphery of the sensorassembly 210, the outer region of conductive material 242 makesresistive contact with the surface of entity whose signal is beingmeasured or analyzed, thereby serving as the conductive portion of anelectrode component of an electrometer used in a traditional ECG orother electrophysiological detection system. Meanwhile, thenon-resistive contact electric field sensor device 212 operates asdescribed herein and/or as described in the '664 application. Thus, tworoutes are provided for signal acquisition for an ECG system, therebyproviding robustness to the overall system. In various versions of suchan embodiment, the electrode component may be active or passive.Furthermore, it will be appreciated that such a sensor assembly 210 maybe used with other devices as well, such as galvanometers and the like.

FIG. 4A is a schematic diagram of a non-resistive contact sensorassembly 310, or at least a sensor head thereof, in accordance withanother preferred embodiment of the present invention. The sensorassembly 310 includes an electric field sensor device 312 at leastpartially surrounded by, or embedded in, a cover 314, which may be ofanti-triboelectric material. In various respects, the sensor assembly310 and sensor device 312 may have one or more characteristics describedin the '664 application. Furthermore, the sensor device may incorporatecharacteristics of the other sensor devices described herein. The sensordevice 312 of FIG. 4A includes a dry electrode component 316 that isinterior to the cover 314. The sensor assembly 310 may also include oneor more springs 346 disposed in locations that, when biased by anexternal structure 50, tend to push the sensor assembly 310 against thesurface 20 of an object to which the sensor assembly 310 is beingapplied. This force tends to hold the sensor assembly 310 in place onthe object surface 20, reducing triboelectric effects and the like thatwould otherwise be caused by relative movement of the sensor assembly310. This, in turn, makes accurate acquisition and processing of thetarget signal 30. Various types may be suitable for use as the springs346 of the present invention.

FIG. 4B is a schematic diagram of a non-resistive contact sensorassembly 410, or at least a sensor head thereof, in accordance withanother preferred embodiment of the present invention. The sensorassembly 410 is similar in many respects to the sensor assembly 310 ofFIG. 4A and includes an electric field sensor device 312 at leastpartially surrounded by, or embedded in, a cover 314, which may be ofanti-triboelectric material. In various respects, the sensor assembly310 and sensor device 312 may have one or more characteristics describedin the '664 application. Furthermore, the sensor device may incorporatecharacteristics of the other sensor devices described herein. The sensordevice 312 of FIG. 4B includes a dry electrode component 316 that isinterior to the cover 314. The sensor assembly 410 also includescompressive material 348 disposed in a location or locations that, whenbiased by an external structure 50, tend to push the sensor assembly 410against the surface 20 of an object to which the sensor assembly 410 isbeing applied. This force tends to hold the sensor assembly 410 in placeon the object surface 20, reducing triboelectric effects and the likethat would otherwise be caused by relative movement of the sensorassembly 410. This, in turn, makes accurate acquisition and processingof the target signal 30. Materials suitable for use with the presentinvention as a compressive material 348 may include rubber, felt,elastomeric, polymeric, closed cell foam and analogues, mechanicalsprings made out of polymers, metals, fibers, or any other material nowknown or hereafter developed that performs the function in an equivalentmanner.

It will be appreciated that the external structure 50 that biases thesensor assemblies 310,410 of FIGS. 4A and 4B against the object surface20 may be a portion of a helmet, belt, article of clothing, furniture,vehicle seating, or the like. With regard to vehicle seating, it will beappreciated that such seating could include seating for automobiles(including trucks), boats and other watercraft, rail locomotives,airplanes, motorized and non-motorized wheelchairs, and other vehicles.

A further embodiment is to use multiple sensors in an array so that ifone or more signals is compromised by interference or otherwise with thesensor/s or its/their data acquisition then other sensors within thearray can be used to gain a useful signal.

FIG. 5A is a fragmentary, partially schematic top view of a portion of awearable sensor belt 500 in accordance with one or more preferredembodiments of the present invention. As shown therein, the wearablesensor belt 500 includes a sensor assembly 510 mounted on a tensioningbelt 502. The tensioning belt 502 that is sized to facilitate the belt500 being fastened around a portion 20 of a human body (shown in FIG.8), such as a thoracic region (chest, upper back, or the like), head,arm, leg, or the like. The tensioning belt 502 preferably includes atleast one elasticated section to assist in maintaining the sensorassembly snugly against the region 20 of the body being monitored. Inaddition to the elasticated section, the belt 502 may include one ormore tensioning devices 504 disposed in the vicinity of the sensorassembly 510 in order to help provide additional biasing force to holdthe sensor assembly 510 against the body 20. However, in someembodiments, such as that shown in FIG. 5B, the tensioning devices areomitted. Furthermore, the belt 502 may include a buckle, hook and loopfasteners (VELCRO®), or the like (not shown) in order to provide abetter overall fit, provide greater biasing force against the sensorassembly 510, position the sensor assembly 510 better, or the like.

FIG. 6 is a fragmentary, partially schematic front view of the wearablesensor belt 500 of FIG. 5A. With reference to FIGS. 5A and 6, the sensorassembly 510 includes a plurality of electrodes 516 that are containedwithin, but exposed to the exterior of, a sleeve 514 that is resistantto triboelectric charging with human skin 20. In at least someembodiments, the sleeve 514 is made from neoprene. Also contained withinthe sleeve are one or more processing and communications components 562,one or more batteries 564, and various electrical connections 566. In atleast some embodiments, the processing and communications 562 and mostor all of the electrical connections 566 are provided in the form of aprinted circuit board. The processing and communications components 562preferably include wireless communication capabilities such as thoseprovided via BLUETOOTH®, ZIGBEE®, or the like. The electrodes 516,processing and communications components 562, battery or batteries 564,electrical connections 566, and surrounding sleeve 514 together define asensor casing 515.

The sensor assembly also includes a support wall 570 on which some orall of the various other components are carried. In some embodiments, ashelf 572 extends from the support wall 570 and provides support for thesensor casing 515. In some embodiments, a flange attachment 576 extendsfrom the support wall 570 and mates with a corresponding groove, recess,or the like in the sensor casing 515. In this regard, FIG. 7 is afragmentary, partially schematic front view of the wearable sensor belt500 of FIG. 6, shown with the sensor casing 515 removed, therebyrevealing the flange attachment 576. In some embodiments, including theone illustrated herein, both are provided. The support wall 570 may, forexample, be constructed from a semi-rigid material such aspolycarbonate. The shelf 572 likewise may, for example, be constructedfrom a semi-rigid structure, which may or may not be of the samematerial as that used for the support wall 570. Materials suitable foruse in the support wall 570 and/or shelf 572 include plastics, such aspolycarbonate; synthetic fibers, such as KEVLAR®; composites; layeredcomposites; and the like. One possible exemplary construction mayinclude carbon Kevlar with other materials such as cotton orpolycarbonate layered in between.

In order to help ensure that the electrodes 516 themselves remainpressed against the skin surface 20 to which they are being applied, oneor more biasing structures may be provided so as to transfer the forceapplied by the tensioning belt 502 to the electrodes 516. Such biasingstructures may include a spring 578, a solid body 580 of a compressivematerial, or the like. Materials suitable for use in such a body 580include neoprene closed cell foam, neoprene, and the like. As shown inFIG. 5A, two or more such structures 578,580 may be utilized incombination with each other.

In use, the wearable sensor belt 500 is attached around the body partwith the electrodes against or adjacent the skin 20. FIG. 8 is afragmentary, partially schematic top view of the portion of the wearablesensor belt 500 of FIG. 5A, shown in use against the chest of a human.As shown therein, the belt 502 has been tightened against the chest. Thetensioning devices 504 assist in making sure that the electrodes 516 areheld against the skin 20, as are the springs 578 and compressible bodies580. The sensor assembly 510 is thus positioned reliably against theskin surface 20, with the electrodes 516 remaining in contact evenduring vigorous activity by the wearer.

FIG. 9 is a front perspective view of a an exemplary wearable sensorbelt 700 attached around the chest 720 of a human wearer in accordancewith one or preferred embodiments of the present invention, and FIG. 10is a fragmentary front perspective view of the wearable sensor belt 700of FIG. 9. As shown therein, the wearable sensor belt 700 includes asensor assembly mounted on a tensioning belt 702. In at least someembodiments, the tensioning belt 702 may have some or all of thecharacteristics described with regard to the tensioning belt of FIG. 5A.The sensor assembly includes a pair of electrode assemblies 716, aprocessing and communications component assembly 762, and a batteryassembly 764. Each electrode assembly 716 includes at least oneelectrode having characteristics similar to those of electrodesdescribed elsewhere herein, including the electrodes 516 of FIG. 5A.Likewise, the processing and communications component assembly 762includes processing and communications components having characteristicssimilar to those described elsewhere herein, including those of theprocessing and communications components 562 of FIG. 5A, and the batteryassembly 764 may include a battery like the battery 564 of FIG. 5A. Inat least some embodiments, the processing and communications components,battery, and electrodes are connected to one another via ribbon wiring766. One or more of the communications component assembly 762, thebattery assembly 764, the electrode assemblies 716, and/or the ribbonwiring 766 may be encased in a triboelectric charging-resistant case orsleeve, including that described with respect to the wearable sensorbelt 500 of FIG. 5A.

FIG. 11 is an exploded fragmentary front perspective view of thewearable sensor belt 700 of FIG. 10, and FIG. 12 is an explodedfragmentary rear perspective view of the wearable sensor belt 700 ofFIG. 10. As shown therein, each electrode assembly 716 includes a clip708 to fasten the main body 706 of the electrode to the belt 702.Furthermore, the housing components 763,765 of theprocessing/communications assembly 762 and battery assembly 764,respectively, may be fastened to the belt 702 via a snap assembly,wherein a button 776 for each is disposed on the belt 702, and acorresponding prong 777 is disposed on the back of each set ofrespective housing components 763,765.

Various advantages may be achieved using one or more of the foregoingembodiments of the present invention. The robustness of the measurementof the electrical signature of an entity or sub-component of that entitymay be increased. A signal being measured or analyzed may be protectedcloser to the source, thereby protecting it from corruption. Thestability of the signal may be enhanced. The signal-to-noise ratio foran electric field sensor may be enhanced. The effect of electrostaticcharge interference with an electric field sensor may be minimizes oreliminated entirely. The use of electric field sensors during exerciseand daily activities may be increased, as can the usability of electricfield sensors with different types of clothing and when clothing ismoving due to exercise or external forces (like wind). Similarly, theusability of electric field sensors may be increased when there isexternal contact that would otherwise knock the sensor loose or thatwould result in charge transfer to the entity being measured oranalyzed. Conversely, the likelihoods of contact electrification, sensorDC drift, and sensor saturation may all be decreased.

Based on the foregoing information, it will be readily understood bythose persons skilled in the art that the present invention issusceptible of broad utility and application. Many embodiments andadaptations of the present invention other than those specificallydescribed herein, as well as many variations, modifications, andequivalent arrangements, will be apparent from or reasonably suggestedby the present invention and the foregoing descriptions thereof, withoutdeparting from the substance or scope of the present invention.

Accordingly, while the present invention has been described herein indetail in relation to one or more preferred embodiments, it is to beunderstood that this disclosure is only illustrative and exemplary ofthe present invention and is made merely for the purpose of providing afull and enabling disclosure of the invention. The foregoing disclosureis not intended to be construed to limit the present invention orotherwise exclude any such other embodiments, adaptations, variations,modifications or equivalent arrangements; the present invention beinglimited only by the claims appended hereto and the equivalents thereof

What is claimed is:
 1. A non-resistive contact sensor assembly,comprising: (a) an electric field sensor device, including a dryelectrode component for receiving an electrical signal from an object ofinterest by capacitively coupling with the entity; (b) a housing inwhich the signal processing component is surrounded or embedded; and (c)an anode and a cathode, distinct from the dry electrode component, thattogether provide a stable surface field, thereby allowing more focusedacquisition of the electrical signal from the object of interest.
 2. Thenon-resistive contact sensor assembly of claim 1, wherein the distinctanode and cathode are disposed in the housing with the dry electrodecomponent.
 3. The non-resistive contact sensor assembly of claim 1,wherein the distinct anode is exterior to the housing.
 4. Thenon-resistive contact sensor assembly of claim 1, wherein the distinctcathode is exterior to the housing.
 5. The non-resistive contact sensorassembly of claim 1, wherein the stable surface field is subtractedcomputationally during post-acquisition processing of the electricalsignal from the object of interest.
 6. The non-resistive contact sensorassembly of claim 1, wherein the assembly is in the form of a sensorhead.
 7. The non-resistive contact sensor assembly of claim 1, whereinthe stable surface field is provided based upon a preliminaryexpectation of one or more conditions when the sensor assembly is beingused.
 8. The non-resistive contact sensor assembly of claim 7, whereinthe stable surface field is provided by altering signal waveform.
 9. Thenon-resistive contact sensor assembly of claim 7, wherein the stablesurface field is provided by altering signal frequency.
 10. Thenon-resistive contact sensor assembly of claim 7, wherein the stablesurface field is provided by altering signal amplitude.
 11. Thenon-resistive contact sensor assembly of claim 1, wherein the stablesurface field is provided based upon detection of one or more conditionsduring use of the sensor assembly.
 12. The non-resistive contact sensorassembly of claim 11, wherein the stable surface field is provided basedon detection of a differing signal during use of the sensor assembly.13. The non-resistive contact sensor assembly of claim 11, wherein thestable surface field is provided based on detection of noise during useof the sensor assembly.
 14. The non-resistive contact sensor assembly ofclaim 11, wherein the stable surface field is provided based ondetection of movement data during use of the sensor assembly.